1. Field of the Invention
The invention relates to retention and deployment systems for canards and more particularly to systems and methods for retaining and deploying canards and canard covers on a projectile.
2. Description of Related Art
During the launch of a projectile it is desired to have retractable canards which are retained within the projectile and subsequent to launch the canards unfold from within the projectile and extend into the airstream. Slots in the projectile housing are provided to accommodate deployment of the canards from within the projectile to the outside airstream. These slots increase drag on the projectile, reducing the range for the projectile launch, and expose the inner components to environmental conditions, such as electromagnetic interference. To solve these problems, slot covers can be used.
Existing mechanisms for canard cover ejection and canard deployment on launched projectiles are known in the art. In the past, mechanisms for canard deployment typically employ multiple pyrotechnics to eject the canard cover and additional spring-loaded mechanisms to deploy the canards. Using separate pyrotechnics and spring-loaded mechanisms to eject the covers and deploy the canards makes it difficult to synchronize the deployment of the canards, therein creating instability if one canard deploys before another, and increases the cost and the complexity of the deploying mechanism.
More recently, efforts have been made to deploy canards using a single pyrotechnic device, for example, as disclosed in U.S. Pat. No. 6,880,780 to Perry et al. (hereinafter, ‘Perry’). Perry discloses an apparatus using covers for controlled storage and deployment of the steering fins of a missile. The covers in Perry serve to prevent the fins from deployment while also providing an aerodynamic fairing. As part of the apparatus, Perry discloses rotatable latch arms for securing the covers. The disclosed rotatable latch arm includes parallel latch arm portions on opposite sides of the fin. The latch arm portions are joined together at only one end forming an open slot. The fins remain in the slot while being retained by the cover. But, when the cover is removed, the fins deploy. This design does not account for situations where the covers are accidentally ejected during or after launch, but before it is desired to have the canards released. When the covers are accidentally ejected and canards accidentally released, control over the projectile can be lost. In addition, to radially project the cover using the latch arm of Perry, a separate extending forward portion of the latch arm is positioned to contact an inwardly extending portion of the cover. This added geometry takes up additional space, adds complexity to manufacturing and uses more material, which adds weight and cost.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for systems and methods that allow for improved performance, and a retaining and deployment system that is easy to make, use and test. Therefore, it would be advantageous to provide systems and methods for retaining and deploying canards and canard covers that overcome the disadvantages associated with traditional canard retaining and deploying systems and methods and solves the challenges associated with such traditional systems and methods, such as accidental canard deployment. The present invention provides a solution to these problems.